#!/usr/bin/env python
import os
import re
import sys

from dateutil.zoneinfo import rebuild

SERVER = "ftp.iana.org"
DIR = "/tz"
NAME = re.compile("tzdata(.*).tar.gz")

def main():
    if len(sys.argv) == 2:
        tzdata = sys.argv[1]
    else:
        from ftplib import FTP
        print("Connecting to %s..." % SERVER)
        ftp = FTP(SERVER)
        print("Logging in...")
        ftp.login()
        print("Changing to %s..." % DIR)
        ftp.cwd(DIR)
        print("Listing files...")
        for name in ftp.nlst():
            if NAME.match(name):
                break
        else:
            sys.exit("error: file matching %s not found" % NAME.pattern)
        if os.path.isfile(name):
            print("Found local %s..." % name)
        else:
            print("Retrieving %s..." % name)
            file = open(name, "w")
            ftp.retrbinary("RETR "+name, file.write)
            file.close()
        ftp.close()
        tzdata = name
    if not tzdata or not NAME.match(tzdata):
        sys.exit("Usage: updatezinfo.py tzdataXXXXX.tar.gz")
    print("Updating timezone information...")
    rebuild(tzdata, NAME.match(tzdata).group(1))
    print("Done.")

if __name__ == "__main__":
    main()